2.1 Recombinant DNA Technology
Recombinant DNA technology involves insertion of specific DNA sequences into a DNA vehicle (vector) to form a recombinant plasmid. Generally, the inserted DNA sequence is foreign to the recipient DNA vehicle, i.e., the inserted DNA sequence and the DNA vector are derived from organisms which do not exchange genetic information in nature, or the inserted DNA sequence may be wholly or partially synthetically made. In recent years several general methods have been developed which enable construction of recombinant plasmids. For example, U.S. Pat. No. 4,237,224 to Cohen and Boyer describes production of such plasmids using restriction enzymes and methods known as ligation. These recombinant plasmids are then introduced into unicellular organisms by means of transformation. Because of the general applicability of the techniques described therein, U.S. Pat. No. 4,237,224 is hereby incorporated by reference into the present specification.
Another method for introducing recombinant plasmids into unicellular organisms is described by Collins and Hohn in U.S. Pat No. 4,304,863 which is incorporated herein by reference. This method utilizes a packaging/transduction system with bacteriophage vectors.
The recombinant plasmids so produced can then be used to transform or "infect" cells in which the plasmid is compatible, resulting in introduction of the foreign gene into the cell. The recombinant plasmid must be capable of autonomous replication in the host cell and should have a marker function which allows the selection of host cells so transformed by the recombinant plasmid. If all of the proper replication, transcription and translation signals are correctly arranged on the plasmid, the foreign gene will be properly expressed in the transformed cells and their progeny.